DefinePK

Abstract

In this study the Eocene Nisai Formation at its type section, (Kazha Mirzai, Qilla Saifullah) in western Balochistan, Pakistan, is investigated for larger benthonic foraminiferal biostratigraphy. Thirty-four species belonging to twenty-five different genera have been identified from the limestone at lower and uppermost of this stratigraphic unit, whereas the middle argillaceous part is devoid of larger benthonic foraminifera. The lower part consists of an assemblage of Asterigerina rotula, Sphaerogypsina globula, Austrotrillina eocenica, Rotalia trochidoformis, Ranikothalia nuttalli, Lockhartia hunti, Assilina sublaminosa, Assilina leymeriei and Assilina subspinosa, Eorupertia spp., Pellatispira spp., Linderina spp. and Asterigerina spp., which suggests Middle Eocene age spanning between zone SBZ-13 and SBZ-18. The upper part has yielded an assemblage that consist of Nummulites fabianii and species of Heterostegina, Calcarina, Pellistella, Asterocyclina, Austrotrillina, Amphistegina, Discocyclina and Operculina which suggests a Late Eocene (Priabonian) age.